Among the various video display systems available in the art, an optical projection system is known to be capable of providing a high quality display in a large scale. In such an optical projection system, light from a lamp is uniformly illuminated onto, e.g., an array of M.times.N mirrors. The array of M.times.N mirrors is mounted on an array of actuators which includes a corresponding number, i.e., M.times.N, of actuators such that each of the mirrors is coupled with each of the actuators. The actuators are made of an electrodisplacive material such as piezoelectric or electrostrictive material which deforms in response to an electric field applied thereto.
When a reflected light beam from each of the mirrors is incident upon an aperture of a baffle, by applying an electrical signal to each of the actuators, the relative position of each of the mirrors to the incident light beam becomes altered, thereby causing a deviation in the optical path of the reflected beam from each of the mirrors. As the optical path of each of the reflected beam is varied, the amount of light reflected from each of the mirrors which passes through the aperture is changed, thereby modulating the intensity of the beam. The modulated beams through the aperture are transmitted onto a projection screen via an appropriate optical device such as a projection lens, to thereby display an image thereon.
Each of the actuators for use in the above-described optical projection system is conventionally made of multiple layers of an electrodisplacive material which are made to deform by the application of an electric field between them.
The multiple layer structure used in such actuators has been normally manufactured by: (1) producing layers of electrodisplacive material having a specified thickness by tape casting a slurry thereof, (2) coating on one side of the individual layers with an electrically conductive material in a pattern to produce an electrode of predetermined dimensions in the completed actuators, (3) stacking the layers of electrodisplacive material coated on one side thereof with a specific electrode pattern and pressing into a block, (4) sintering the block while it is held under pressure, and (5) dicing the sintered block to produce the multiple layer structure.
The electrode patterns in alternating layers are then externally connected to permit an electric field to be generated between the layers of electrodisplacive material.
There is a number of problems associated with the prior art manufacturing method described above, however. First of all, the complicated nature of the process often results in producing one or more defective layers which fail to exhibit the desired mechanical deformation characteristics. In addition, the presence of continuity defects in the electrode patterns may force the scrapping of such defective actuators, entailing wasted materials and labor spent in the fabrication and quality control test thereof.
Another problem present in the prior art method is that it requires expensive electrode materials having high melting points such as platinum(Pt) or palladium(Pd) so as for the electrode pattern to withstand an extremely high sintering temperature, e.g., 1,250.degree. C. or higher.